I have recently gotten my Rem 700 back from my smith. (.223, .250 neck, trued action, Kreiger LV taper barrel 1 in 14 twist) I have begun load testing, and it does show promise, with 3 shot groups averaging in the upper 2's. Only thing is though, I am getting somme pretty good primer cratering at moderate loads and up. This is happening without the primers flatening noticably at all. This didn't happen before I had the work done, with the same loads, although it did have a 1 in 12 twist barrel originally. I understand that the different twist can have an effect on pressure, but there are virtually no other pressure signs besides the heavy cratering. Any thoughts? Thanks, ol blue

Ol Blue,

A slower twist generally means less pressure, everything else being equal.

Primer cratering can occur even with mild loads if there is too much clearance between the firing pin and its hole in the bolt face.

Did your gunsmith square the bolt face as a part of the process?

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I know the next rifle will be perfect.......

Thanks NJ1MG.Yes he did square the bolt face. That is one thing I was thinking could be a possibility. If the FP hole was slightly tapered, taking material off the face could have the effect of enlarging it? I have taken the firing pin out and seen how it fits the hole from the front, there doesn't appear to be much if any slop there, but dont really know how tight it should be. Is this what you are thinking has happened? Thanks

I hope that "upper 2's" means upper 2/10ths of an inch and NOT 2 inches!

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http://stevespages.com/page8.htm

If it was 2 inches I WOULD be worried!

The one thing I didn't ask is whether this only happens when you are fireforming cases--you could have just a tad of extra headspace that might contribute to some primer cratering.

IMO, you should consult your gunsmith about it. If it didn't do it before, it shouldn't do it after.

The benchrest guys will sometimes install a bushing in the bolt face to get the firing pin clearance to be "just right".

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I know the next rifle will be perfect.......

I am on my second firing of these cases in this rifle, neck sizing only. I have checked the headspace and it seems good. I have talked to my smith and we will be looking into it soon so will post what we find out. Thanks, ol blue

OL' BLUE,
Another cause of cratering is a weak firing pin spring. If the rifle were left in the cocked condition for a protracted period of time, it may well have lost some of it's strength. Good luck.

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BigBob

[ 06-15-2002, 02:25: Message edited by: centerpunch ]

There are a bunch of things that can caused cratered primers some having to do with the rifle and some not.
Spring too weak. Firng pin nolonger supports cup.
Spring too strong. Firing pin penetrates cup excessively and bounces back after bottoming.
The use of a titanium pin. Lack of inertia in striker offers less support to primer.
Soft primers. Self explanatory.
Firing pin too sharp.
Firing pin too flat.
Sometimes the gunsmith may do some work with a center in the firing pin hole and will bevel the hole.
Bad Kharma. Sometimes the reason for cratered primers is a mystery and must be related to cosmic payback in some way.
Seriously, I would check the firing pin hle first, the spring second, and consider switching primer brands. It is usually impossible to crater a Remington while Federals were born to crater. Regards, Bill.

How does a weak firing pin spring cause cratering????

Well, I hope it's not bad karma! I think it is a good possibility that the fp spring is weak, and that is the direction we are going in first. It is interesting that you say it is impossible to crater a Rem. primer. My experience is just the opposite. I tried Fed. 205m's, CCI br4's, and Rem 7.5's. The CCI's cratered the least, followed by the 205's, the Rems were the worst to crater. Go figure. Thanks to all who replied.... ol blue